I think the maclaurin series question was cosh(x) = 1 + x^2/2 + x^4/24 and so cosh(ix) is the same as cos(x)
for the graph of x = cosh (y+b) I got a parabola on the positive x-axis that had its minimum point at (1,0) translated down by the constant b. hence the minimum distance to the y-axis would be 1 unit
r = k / sin(theta) can be rearranged to give rsin(theta)=k which is just y=k, so a horizontal line
the proof by induction question involving the matrices could be done by multiplying A^k by A again
these are the only ones I remember off the top of my head!!